Patent GB-699023-A (GB)
Title: Process and apparatus for the manufacture of acetylene from calcium carbide and water with the simultaneous production of dry calcium hydroxide
IPC: C01F11/02
Filed: 1950-10-05
Abstract: <PICT:0699023/IV (b)/1> Acetylene is prepared from the reaction of calcium carbide and water with the simultaneous continuous formation of dry calcium hydroxide, the reaction heat being carried off by the evaporation of a certain surplus of water and the decomposition taking place in one apparatus but in two stages, the process being characterized in that the acetylene produced in the first decomposition stage by decomposing carbide with water, and the acetylene produced in the second stage by decomposing the carbide contained in the separated calcium hydroxide with water, are withdrawn in two independent measurable gas currents at any desired temperature, to determine the quantity of water required for the second stage reaction, the two necessary gas chambers are continuously separated one from the other by means of a gas-tight material sealing of at least 2 metres in height, the sealing being formed continuously from the solid mixture consisting of calcium hydroxide and undecomposed fine carbide resulting from the first stage reaction, and contact is avoided between the solid mixture and the air or protective gas.  The carbide employed in the above process may have a high dust content.  An apparatus for carrying out the above process may consist of for the first decomposition stage a rotating, slightly inclined drum equipped with sieves, bars, grates, slits or holes, encased in a stationary gas-tight jacket tapering conically towards the bottom, in the lower part of which there is a conveyer device serving at the same time as a mixer for the calcium hydroxide and fine carbide falling from the inclined drum, or the first stage apparatus may consist of a sieve or several sieves agitated regularly or irregularly, possibly arranged one under the other and of flat or arched design, consisting of wire mesh, bars, grates, slotted or perforated plates, or the first stage apparatus may consist of a separating gas current device which circulates generated acetylene through a ventilator beneath the carbide employed in the first stage to carry off the fine undecomposed carbide still contained in the calcium hydroxide together with the calcium hydroxide to the second stage reaction via the gas-tight seal.  The apertures through which the calcium hydroxide and carbide mixture fall are preferably over 3 mm. in width extending over the whole length of the decomposition apparatus, and water is introduced at a point a third or quarter of the way down the apparatus.  The apparatus for the second stage may consist of a chamber, into which water is fed, fitted with a worm, a rotating drum, swing channels, or several plates arranged one beneath the other on the lines of a wedge oven, and the plates can either be fixed with the reaction mixture moved by rotating agitators equipped with shovels set at a suitably oblique angle, or the plates can rotate and fixed agitator arms or laterally installed worms effect the movement of the reaction mixture, and the plates are surrounded by an edge on the discharge side in order to extend the stay of the carbide contained in the mixture.  The gas-tight sealing between the two gas chambers may be formed by a container installed above the second stage chamber and the material separated from the first stage reaction is conveyed uninterruptedly into the container by an obliquely or vertically installed conveyer, and material from the container is conveyed to the second stage chamber by means of an adjustable apportioning apparatus.  The container may be of circular cross-section and may be widened towards the top to act as a store silo for the calcium hydroxide and carbide mixture from the first stage reaction.  The amount of water required for the second stage reaction and to carry off the heat of reaction may be determined by a device for measuring continually the power consumption required to drive the agitating device either by the amount of current required to drive an electric motor attached to the agitating device or by means of a manometer attached to the agitating device, the addition of water being decreased on an increase of power consumption and increased when the power consumption decreases.  Electric thermometers may be installed at places where the first stage decomposition takes place, particularly in the vicinity of adjustable water nozzles, to facilitate the determination of the amount of water required in the second stage.  In the Figure, the carbide container 1 is provided with ball closures to deliver carbide into container 2, and the carbide is delivered to the inclined rotating drum 5 via the adjustable apportioning bucket wheel 3 and shaking channel 4. Some of the carbide falls on to the transport device 6 which forms the base of a gas-tight stationery jacket 7 tapering towards the bottom.  The water is distributed by atomizing nozzles 9, each atomizing nozzle being separately controlled.  Acetylene generated passes through tube 10 equipped with a clearance screw 11 to washing tower 12 and cooling tower 13.  Any particles of carbide carried over with the acetylene are decomposed in the tower 12 with the washing water.  The quantity of gas generated is measured by baffle 17.  The calcium hydroxide and carbide discharged from the drum are conveyed by the transport and mixing device into the storage container 18 where a material level of at least 2 metres is maintained.  The material is then conveyed by means of the adjustable bucket-wheel 19 and the worm conveyer 20 via the aperture 21 into the acetylene developer 22 for the second stage reaction.  The quantity of water for the second stage reaction and carrying off the heat of reaction is fed on to the top plate of the series of plates in the developer 22 by means of the atomizing nozzles 24.  The material is gradually passed through developer 22 with the aid of the agitator arms 25 equipped with obliquely adjusted shovels.  Calcium hydroxide collects in sluice 28 and acetylene is fed off through pipe 31 to the washing tower 32, then to the cooling tower and is measured by baffle 33. Thermometers and means for measuring power consumption are not shown in the drawing. Specification 306,042, [Class 2 (i)], is referred to.